1. Technical Field
The present invention provides an analog to digital conversion device and an analog to digital conversion method, and more particular to an analog to digital conversion device and an analog to digital conversion method using a subranging concept.
2. Related Art
In recent years, with the development of science and technology, portable electronic products develop vigorously. In order to provide long operating time, relevant researches on design of integrated circuits with low power consumption have attracted much attention. In the structure of an electronic product, an analog to digital converter (ADC) is one of the important circuits, and therefore, the power consumption of the ADC attracts much attention.
There are many types of ADC with different structures, for example, a flash ADC, a pipeline ADC, a successive approximation register (SAR) ADC, and a two-step ADC, each of which has appropriate application range.
Among various ADC structures, a SAR ADC merely uses one comparator in conversion, has a simple structure, and needs a relatively small number of elements, so that the SAR ADC has a power saving advantage and has found wide application in portable electronic products.
With the development of science and technology, functions of electronic products become increasingly complex and strong, and therefore the resolution requirements of the ADC are increased accordingly. However, the higher the resolution requirements are, the larger the number of bits needed in the SAR ADC is needed, resulting in a larger capacitor array. Because the power consumption of switching of the capacitor array occupies the largest proportion in the power consumption of the SAR ADC, for the SAR ADC, the improvement of a resolution results in an increase of the overall power consumption.
Therefore, how to provide a SAR ADC with a high resolution and low overall power consumption to prolong the operating time of a portable electronic product becomes an important topic of concern for persons skilled in the art.